Conventionally, there is known a liquid supply device which supplies liquid such as a coating material in a specified amount.
This liquid supply device includes a cylinder body having two openings, a sliding block which is slidable on the inner wall surface of the cylinder body, an electric actuator, and a fluid pressure cylinder. The electric actuator includes a driving rod coupled to the sliding block in such a manner that the driving rod is extendable and retractable along the axis of the cylinder body. The electric actuator is placed on the axis of the cylinder body at a location that is outward relative to one end portion of the cylinder body. The electric actuator operates to drive the sliding block. The fluid pressure cylinder includes a piston rod coupled to the sliding block in such a manner that the driving rod is extendable and retractable along the axis of the cylinder body. The fluid pressure cylinder is placed on the axis of the cylinder body at a location that is outward relative to one end portion of the cylinder body. The fluid pressure cylinder operates to drive the sliding block.
To supply liquid in a specified amount, the electric actuator and the fluid pressure cylinder operate to move the sliding block along the axis of the cylinder body. This allows the liquid to flow into one of two inner space formed by comparting the inner space of the cylinder by the sliding block, through one of the openings, and discharge the liquid from the other inner space through the other opening.